<template>
  <PageWrapper class="virtual-scroll-demo">
    <Divider>基础滚动示例</Divider>
    <div class="text-center mb-4">
      <a-button @click="vScrollRef?.scrollToTop()">滚动到顶部</a-button>
      <a-button @click="vScrollRef?.scrollToBottom()" class="mx-2"
        >滚动到底部</a-button
      >
      <a-button @click="vScrollRef?.scrollToItem(scrollToItemIndex)"
        >滚动到第
        <input-number
          v-model:value="scrollToItemIndex"
          class="!w-60px mx-1"
          :min="1"
          :max="data.length"
          :precision="0"
          size="small"
          :controls="false"
          @keydown.enter="vScrollRef?.scrollToItem(scrollToItemIndex)"
        />
        条
      </a-button>
    </div>
    <div class="virtual-scroll-demo-wrap">
      <VScroll
        :itemHeight="41"
        :items="data"
        :height="300"
        :width="300"
        ref="vScrollRef"
      >
        <template #default="{ item }">
          <div class="virtual-scroll-demo__item">
            {{ item.title }}
          </div>
        </template>
      </VScroll>
    </div>

    <Divider>即使不可见，也预先加载50条数据，防止空白</Divider>
    <div class="virtual-scroll-demo-wrap">
      <VScroll
        :itemHeight="41"
        :items="data"
        :height="300"
        :width="300"
        :bench="50"
      >
        <template #default="{ item }">
          <div class="virtual-scroll-demo__item">
            {{ item.title }}
          </div>
        </template>
      </VScroll>
    </div>
  </PageWrapper>
</template>
<script lang="ts" setup>
import { PageWrapper } from "@/components/Page";
import { VScroll } from "@/components/VirtualScroll";
import { Divider, InputNumber } from "ant-design-vue";
import { ref } from "vue";

const vScrollRef = ref<typeof VScroll>();
const scrollToItemIndex = ref(1000);

const data = (() => {
  const arr: any[] = [];
  for (let index = 1; index < 20000; index++) {
    arr.push({
      title: "列表项" + index,
    });
  }
  return arr;
})();
</script>
<style lang="less" scoped>
.virtual-scroll-demo {
  &-wrap {
    display: flex;
    justify-content: center;
    margin: 0 30%;
    background-color: @component-background;
  }

  &__item {
    height: 40px;
    padding: 0 20px;
    border-bottom: 1px solid @border-color-base;
    line-height: 40px;
  }
}
</style>
